Never had a P11, but did have a P40. Most frustrating experience I have had where guns are concerned. Out of the box, I could get three rounds through it, max, before it malfunctioned. This occurred with a cross-section of quality factory ammo. Tried a couple of things to help, but nothing worked. It was, as a practical matter, a single shot.
Finally, in strict accordance with the instructions in the owners manual, I returned the gun to Kel-Tec. Weeks passed, and I heard nothing. I wrote to see what had happened to my gun --was not told what had been done to it, but rather was informed simply that it would be returned at my expense (after I had agreed to certain things), as opposed to at Kel-Tec's expense (as per the owners manual).
(Apparently UPS raised rates during that period, and Kel-Tec departed from the representations in the manual relative to who paid for what.) At that point, some more letter writing followed, and I guess K-T realized that I was serioulsy ticked off and was going to do something about it if the gun was not returned "right quick" at K-T's expense as originally represented when I sent it back to them. At all costs UPS delivered the gun to my front door (at K-T's expense), and I took it to the range.
Put fifty rounds through it with only one or two malfunctions, so I guess it was "fixed." But, as I put it in the case to return home, I noticed that the recoil spring--almost all of it (the bigger one) was hanging out the front of the gun. Took it home and tried to cure the problem. Back to the range: after two or three shots, the springs again came out the front of the gun. At that point, I took it to a dealer who was willing to take the p.o.s in trade on something else. It thus became the only gun of any kind I have ever bought and then, in all honesty, simply dumped. Mine must have been untypical, but it was an absolute, categorical piece of junk. As I said at the beginning of this rant, I have never had a P11. And it's an absolute certainty that I won't ever have one!